The present invention is directed to an expansion anchor or dowel formed of an axially extending anchor body with a first end section to be inserted first into a bore hole in a receiving material and an opposite second end section. The second end section contains a load application means. The anchor body has an axially extending expansion region in the first end section formed of at least two axially extending tangs separated from one another by slots. Further, the first end section contains a recess in which an expanding body is received for radially outward expansion of the expansion region when the expanding body is displaced toward the second end region.
In fastening techniques, expansion anchors or dowels are frequently used formed of an anchor sleeve with an expanding region. Axial slots enable the expanding region to be expanded radially outwardly by an expanding body displaced axially in a through hole in the anchor sleeve. The through hole in the expanding region and/or the expanding body have/has a conical shape. The expansion of such known expansion anchors in a through hole takes place usually by a pulsating displacement of the expanding body in the through hole in the expanding region. During displacement, the expanding body can be received completely within the through hole. For such an embodiment of the expansion anchor, additional loss protection for the expanding body is generally required. The expansion takes place due to pulsating driving of the expanding body into the through hole. In the expanded state, the expanding body is held by self-locking the angle of inclination of the conical surfaces is relatively flat. To obtain the required expansion forces, the expanding body must be relatively long and often assumes about half the axial length of the expansion sleeve. As a result, only a relatively short length of the sleeve is available for screwing in a threaded rod and any further adjustment is very limited. As a result of the relatively small depth available for screwing in the threaded rod, there is a problem that the expansion sleeve may break when subjected to a transversely directed load.
In another embodiment, a conically shaped expanding body projects out of the front or leading end of a blind borehole. To expand such an expansion anchor, generally referred to as a "outcone anchor", the anchor sleeve is driven over the expanding body braced against the base the borehole. In the case of "outcone anchors" under load, the expanding body is secured only by friction between the outer surface of the expanding body and the inner surface of the expanding sleeve. The angle of inclination of the conical outer surface of the expanding body must not be larger than the angle of self-locking. To achieve the necessary expansion forces, the expanding body must be made relatively long. As a result of the length of the expanding body, there is the danger that the body will incline and tilt during the setting procedure.